Blackboard composition



; IUUI COATING R PLASTIC. EXAMINER UNITED STATES Cross Reference330, 3

PATENT OFFICE.

LOREN OHADWIOK, OF BATTLE CREEK, MICHIGAN.

.BLACKBOA'RD COM POSITION.

SPECIFICATION forming part of Letters Patent No. 330,375, dated November 12, 1885.

blackboard-surfaces upon the walls of buildings; and it consists in two compositions,which 5 first composition forms the foundation for the blackboard finish, and the second composition constitutes the finishing-coat. These two compositions are previously prepared and mixed in a dry state,and sold in that shapeas articles of manufacture, and are adapted to be applied by any mason when mixed with water.

The ground-work composition is composed of the following ingredients in substantially the proportions given: hydraplig cement I twent poung s sand thirty poun soalclne sTilp ate o f lime en poun s; lime Eve 291 1 s. ese ingredients to be well verized and thoroughly mixed, and when the g o composition is used sufficient water should be added to render i'3ftli"'cons1sency of ordinary plaster. When this foundation composition has been applied to the wall, the

are applied to the walls of the building. The

Application filed September 23, 1885. Serial No. 177,906. (No specimens.)

finishing coat is applied. This consists of the following ingredients in substantially the 5 specified proportions: h draulic cement thirty pounds; calcined surkmmwenty poundslime ten pounds- Black sand twenty poundsi amplaclk three pounds. these ingredien s o e oroughly mixed together, and the composition is ready to be applied-on being mixed with water.

' The hydraulic cement used is preferably the finest grade of English Portland cement, especially for the finishing-coat.

I claim as my invention- 1. A blackboard composition which contains hydraulic cementas an essential ingredient.

2. Afinishing blackboard composition composed of hydraulic cement, calcined sulphate of lin1e'lime,bl'ac san ,andTariff-bidcl ,s'ub stamina Iris set forth. I i

3. A blackboard dressing consisting of a foundation-coat of hydraulic cement,sand,calciued sulphate of lime, and lime, anda finishing-coat composed of hydraulic cement, calcined sulphate of lime, lime, black sand, and lamp-black, substantially as set forth.

In testimony whereof I afiix my signature in presence of two witnesses.

7 LOREN GHADWIOK. Witnesses:

NATHAN H. BRIGGS, FRED M. WADLEIGH. 

